Pump



P. L. SCOTT Oct. 3, 1939.

PUMP

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bined cam and eccentric shaft 2.

`Patented Oct. 3, 1939 PUMP Philip Lane Scott, Chicago, Ill., assignorto Super Diesel Tractor Corporation, La Porte, Ind., a corporation ofNew York Application August 7, 1935, Serial No. 35,110

6 Claims.

l This invention relates to fluid pumps and more particularly to highpressure liquid pumps of the type used to deliver fuel to an atomizingvalve in an internal combustion-engine. One object is to provide a pumpin which the quantity delivered may be easily, fully, and accuratelycontrolled by a light mechanism, Another object is to provide a fuelpump in which the time of initiation of delivery may be readily andeasily changed while the pump is in operation and by astructure which isan integral part of the pump itself. Another object is to provide aunitary mechanism for accomplishing both these controls. Another objectis to provide a safety device integral. with this control mechanism.Other objects will appear from time to time. l

The invention is illustrated, more or less, diagrammatically in theaccompanying drawings,

wherein:

Figure 1 is a cross section of such a fuel pump;

Figure 2 is a section taken along the line 2--2 of Figure 1;

Figure 3 is a plan view of the control mechanism, with parts in section,taken at line 3 3 of Figure 1.

Figure 4 is a sectional view showing the control mechanismwith thecontrol valve closed.

Figure 5 is a section, similar toFigure 4, and showing the controlmechanismas it is prior to valve closure. l Like numerals are appliedwith like parts throughout.

In Figure l, 'I is a pump base supporting a com- 3 is ,a cam mountedupon the shaft and 4 is an eccentric mounted adjacentto the cam upon thesame shaft. `."l is a trip lever mounted on the eccentric. 'Ihe nose 6of this lever bears against the tappet rod 1 and against the fulcrumblock 8.

The trip lever has a trip point 9 which may slide across face of theblock 8 and drop oifthe nose I0 ofl this block. The-block 8 is supportedby two eccentric shafts II and I2 which are arranged to provide both'vertical and horizontal \movement of the block 8 for purposes to' bedescribed later.

The block 8 is positioned againstl transverse mothe base I is a pumpIbody I4, having a bore I5 in -which a slider I8 is arranged toreciprocate. .The slider I6 carries at one end a roller I1, adapted tocooperate with the face of the cam 3. The roller is mounted on apin I8and this structure constitutes the cam follower. Insertedin the camfollower is a hardened button I9 which bears against the end or aplunger 20, which is mounted for reciprocation within a barrel 2l whichin turn is screw-threaded into the body I4. 22 is a spring retainerwasher which is iitted around the head of the plunger 20. A spring 23bears against this washer and serves to withdraw the plunger and toreturn the cam foly lower I6 against the receding face of the cam 3. 24is a vent hole leading to the'bore I5. 25 is a suction valve assemblyscrewthreaded into the body I4 and providing an admission means for 10fluid into the pumping chamber 26. 21 is a discharge valve assemblyscrewthreaded into the body I4. 28 is a liquid passage leading from thepumping chamber 28 and closed by a plug 29. 30 is a control valve cagescrewthreaded' into the body I4 and connecting with the fluid passageway28. 3l is a-valve mounted in the cage 30. It is held upon its seat bymeans of the stem 32, the spring 33 and the washer 34. The tension onthe spring is adjusted by means of the nut 35. `The washer 34 iscontacted by a push rod 36, which is arranged to slide in a bushing 3]which is screwthreaded into the cage 30. The push rod 36 may be adjustedin length by means of the nuts 38, 38. The lower end of the push rod 36is contacted by the tappet rod 1 which reciprocates in a bo're in thebase I. The pump body I4 is attached to the base by means of the c apscrews 33, 39. 48 is an outlet discharging from the valve 3| to anyconvenient point, for example to a sump or to some other suitable pointon the suction side of the pump. Heretofore, in the construction ofliquid pumps of the` particular type shown, namely, high pressure liquidfuel pumps intended to deliverliquid fuel to an atomizing valve in anengine, the two essential controls have been considered and made asseparate elements. It is of course necessary in, all internal combustionengines employing injection of fuel to be able to regulate the quantityof fuel from stroke to stroke. In many engines it is also essential tobe able to changethe time of introduction of fuel with respect-to pistonposition or to the angular position of the crank shaft while the engineis in operation.. In allv construcl tions so far employed a separate andindependent tion by the guide members I3, I3. Mounted upon mechanism hasbeen used to accomplish this 'f change in timing. Such mechanisms vhaveproved'` both expensive and cumbersome and have been in the form Aof aseparate device or attachment out- V 50 side the pump proper. One of thepurposes of this invention is tovprovide for both these controls in aunitary mechanism built into the pump'. proper, and further to provide alight and simple Q mechanism to 'accomplish this dual purpose. M7155will be seen from the drawing, the mechanism consists in a trip lever 5which is carried on an eccentric 4 which is mounted on'the same shaftthat carries the driving cam. As this eccentric rotates it imparts anoscillatory motion to the trip lever 5, which during part of the timerides upon the trip block 8 at its nose portion 6, and part of the timerides upon another part of the same block 8 upon its trip point 9. Whenthe point 8 is in contact with block 8, the lever will 'fulcrum aboutthis point, as shown in Figure 4,

causing the nose 6 to rise as the eccentric rotates.

The nose 6 presses against the tappet rod 1, and moves it upward. Thisupward motion is transmitted to the push rod 36 and tothe pre-loadedspring and stem assembly 32, 33, 34, and ultimately to the valve 3|,causing this valve to seat. When the point 3 drops off the trip nose I8of the block 8, as shown in Figure l, it obviously drops the nose 6 ofthe lever 5 and permits the entire train of mechanism just described, todrop, finally permitting the valve 3| to be unseated by pressureexisting in the passage 28 and ultimately in the pumping chamber 26. Theblock- 8 is mounted upon two eccentric shafts which are arranged to movethis block both vertically and horizontally. The eccentric shaft uponrotation, will cause the block 8 to move horizontally backward andforward. Only a small amount of rotation of this eccentric shaft isemployed. Hence only negligible vertical motion occurs for considerablehorizontal motion. As the block 8 is moved horizontally the trip point 9will drop off the nose l0 sooner or later. in the cycle. As the block 8is moved away from the shaft 2 the tripping occurs earlier in the cycle.As it is moved toward the shaft 2 the tripping will occur later in thecycle.

'I he eccentric shaft ward by the eccentric shaft the nose v6 willobviously contact the tappet rod later in the cycle. The eccentric shaftI2 has small angular motion and isarranged to give the maximum amount oflift or vertical motion with 'a minimum -horizontal motion. It will beseen, then, that a movement of either one of these shafts has noappreciable effect upon the functioning of the other shaft, with respectto its particular control of the cycle of operations. 'I'he train ofmechanism which transmits the functioning of the lever 5 to the valve 3is shown in the form of. Figure 1 as merely one convenient mechanismconsisting of two rods and an adjustment, with the exception of theirnportant pre-loaded spring assembly.

It is of course evident that any attempt to'make a rigid train in thisparticular place would re-A quire what would probably be unreasonableac- 'curacies in commercial manufacture. The preloaded spring assemblynot only permits overrun due to inaccuracies in manufacture and assemblywithout damage to the parts but also compensates for the varying strokesof the nose 6 depending upon the position of the block 8. Thispre-loaded spring assembly serves a further important service, namely,it provides a safety'valve which will open when any predeterminedpressure in the pumping chamber 26 is exceeded and thereby preventdamage to the atomizing valve, the high I2 is arranged to move thepressure piping, or to the pump itself which easily result from stoppagein the atomizing valve. 'I'his preloaded spring assembly consists in astem 32, bearing against the end of the valve 3|. This stem carries thespring 33 which abuts against an enlargement upon the stem at one end.At the other end the spring 33 abuts against the cup-shaped washer 34,which is drilled and arranged to slide upon the stem 32. The spring isput under initial load by means of the nut 35. This load is determinedby the maximum permissible pressures in the pumping chamber 26.Sufficient compression is put upon this spring to hold the valve shutagainst the desired pressure under the condition of support of thewasher 34 by the push rod 36 and the tappet rod 1, and in turn the leverand block mechanism already described. When the pusher rod 36 bearsagainst the washer 34 its upward force is transmitted by the washer tothe spring and thenceto the stem 32. The spring is therefore a yieldingmember interposed in an otherwise rigid linkage.

The use and operation of my invention are as follows: y

The operation of the general mechanism of the pump such as the inlet andoutlet valves, cam and cam follower, and so forth are too well known toneed detailed description. The inlet assembly 25 is connected to aliquid supply and the outlet assembly 21 is connected to an atomizingnozzle. As the cam shaft rotates the cam follower is caused alternatelyto rise as the fiat driving face of the cam acts upon the roller, and todrop as the roller follows the receding faceof the cam. The firstmovement obviously causes a discharge `stroke of the pump plunger andthe second movement causes a suction stroke.

'I'he novel features of the inventionl reside largely in the linkagefrom the eccentric 4 through to the valve 3|, which is the control valveof the pump. This valve controls both the timing4 and the quantity.'I'his valve is open just before and at the instant `the plunger beginsto move upward on a discharge stroke. Its being open is due of course tothe relative positions of the lever 5 and the block 8 together with theposition ofthe eccentric 4 at that instant. Since the pumping chamber 26is connected by means of the passage 28 to this valve 3|, when thisvalve is open discharge -will evidently take place through this valveand not through the discharge valve 21 to the atomizer, since the lattercircuit presents a far higher resistance. When such discharge vtakesplace through the valve 3| it may be by-passed back to the fuel tank orin any part of the suction circuit, such piping not being shown indetail since it forms no essential part of the invention and is merely amatter of design convenience. As the eccentric 4 rotates and the lever 5begins to fulcrum about the point 9, the nose 6 rises, and takes up thetrain of -mechanism 1, 36 and 32, 33, 34. The valve 3| is thus lifteduntil it seats firmly and is h eld seated against predeterminedpressure, which are regulated by the adjustment on the spring 33. Ifthese pressures are accidentally exceeded the valve 3| will unseatagainst the spring 33, permitting discharge through this valve andpreventing damage. However, assuming conditions to be normal when thisvalve closes it will stop all flow through passage 28 and compel theentire discharge of the pump to take place through the dischargeassembly 21 and to the atomizing valve. It is the instant at which thisvalve closes with respect to the 'which the pump shaft is permanentlyconnected by gearing or other suitable drive which determines the timingof injection. As this valve 3| closes earlier with respect to the camshaft, injection into the engine will occur earlier and as this valvecloseslater the injection into the'engine will occur later. To cause thevalve 3l to close earlier the eccentric shaft I2 is rotated, to raisethe nose l0 of the block 8 and the face of the block adjacent to thenose. This causes the nose 6 of the lever 5 to contact the tappet rod 1earlier and this in turn causes the train 'of mechanism up to the valve3l to operate and to close the valve earlier. To obtain later timing theeccentric shaft I2 is moved so as to cause the nose 6 to contact thetappet rod later, thereby causing the valve to closelater. As alreadydescribed, the motion of the eccentric shaft i2 has negligible effectupon the second function of control, quantity, since it does not movethe block 8 appreciably to the right or left.

The control of quantity is changing the length of time, or the number ofdegrees with respect to the cam shaft that this valve is held closed.Assuming that a proper timing has been obtained, then as the load on theengine changes and it is necessary to vary the quantity of fueldelivered, the block 8 is moved" to the right or the left by means ofthe eccentric shaft II, the block sliding upon the eccentric shaft l2.-As' the block 8 is moved to the right the trip point 9 of the lever 5will reach the nose l0 of the block 8, and .drop oil! earlier in thecycle. The earlier it drops off the earlier is the valve 3l releasedsince it responds to the .train of mechanism lying between` it and thelever 5. 'I'his means that discharge through this valve will bepermitted earlier in the cycle, at an earlier point in the travel of theplunger on its discharge stroke, and obviously at an earlier point inthe engine cycle. If this valve is allowed to open when the pump plungerhas travelled but half its stroke it is clear that but half the quantityof oil will be delivered as compared to the condition when the valve isheld shut for the entire discharge stroke of the pump plunger. To holdthis valve closed during longer periods of pump plunger travel andthereby obtainlarger and larger quantities of oil the block 8 is movedto the left toward the cam shaft. The trip point 9 will then drop oil!the nose Ill at a later and later time. As described, the horizontolmovement to obtain quantity control has negligible effect on the timeadjustment.

Either or both of these controls may be manually operated and either -orboth the controls may be `governor operated.

It is evident that while I have shownone particular form of such adevice in a complete and operative structure, the principles involvedmay be employed in a wide variety of structures, and the invention istherefore not limited to the particular type shown but may be used lnmany other types of pumps. A

I claim:

. 1. In a fuel pump for/internal combustion engines, a. pump body havinga pumping chamber, a sucton'valve and a separate control valve in'communication with the pumping chamber,

means for.operating said control valve, a pump plunger mounted forreciprocation in the body to perform suction and discharge strokes, adrive for said plunger and a separate drive for said accomplished bycontrol valve. and means for varying both the time of closing andindependently the time of` opening of said control valve during thedischarge g stroke, said varying means comprising a fulcrum block andlever fulcrumed thereon, and parts for raising said fulcrum block andfor independently moving it laterally, while the pump is running, saidlever forming part of the drive for the control valve.

2. AIn a liquid pump, suction and discharge valves, a separate controlvalve for accommodating discharge from the pump during desired portionsof -the discharge cycle of the pump, means for closing the control valveagainst pressure within the pump, said closing means including a stem'engageable with said control valve to close it, a push rod, a yieldingmember interposed between the push rod and said stem to yieldinglytransmit to the control valve force applied to the push rod whereby topermit the control valve to open in response to predetermined pressurein the pump, and means for applying driving force to the push rod duringthe discharge stroke of the pump,'said means including a leverengageable with the push rod and movable in opposite directions totransmit a driving force thereto and to discontinuethe application offorce thereto, respectively, and means cooperable with said leverl forvarying the time of application of said force to said push rod and forvarying the time of release of force therefrom independently whereby thecontrol valve is alternately closed and opened to permit dischargetherethrough at varying times in the discharge cycle of the pump.

3. In a liquid pump, suction and discharge valves, a separate controlvalve, means for closing said control valve at various times in thedischarge cycle of -the pump, said valve closing means comprising astem, a push rod, means for reciprocating the push rod, a yieldablemember intermediate said push rod and said stem, said push rod movingmeans including a fulcrum part and a fulcrum lever arranged to slide andto fulcrum upon said fulcrum part, said adjusting means for said fulcrumpart comprising a pair of eccentric shafts mounted for rotation and inconfor moving said fulcrum part generally laterally for varying the timeof opening and the time of closing of said control valve.

. 4. In a liquid pump having a pumping barrel, independent suction anddischarge valves positioned to control` the entrance and exit of liquidto said barrel, a separate control valve and a mechanical linkage Lorsaid control valve, said linkage including the fclowing elementsarranged each to act upon the succeeding element: a fulcrum member, alever fulcrumed thereon, a push rod, a yieldable member, a valveoperating stem and said control valve, and means including adjustableparts for adjusting said fulcrum member, said lever operating the pushrod towards and away from the valve' operating stem for alternatelycausing closing and opening movements of the valve, said adjustablemeans being eective for independently adjusting the times at suction anddischarge valves positioned to contml.

the entrance and exit of liquid to said barrel, a separate. controlvalve and an independent mechanical linkage for eecting opening andclosing of said control valve, said linkage including the followingelements arranged each to act upon the succeeding element: a fulcrummember, a lever fulcrumed thereon, a push rod, a resilient member and avalve operating stem, said resilient member being positioned betweensaid valve operf ating stem and said push rod, means for rocking thelever to move the push rod towards and away from the valve operatingstem, and means including separate adjustable parts for adjusting saidfulcrum member, said adjustable parts being eflber, suction anddischarge valves positioned in said passages to admit and dischargeliquid, a third passage communicating with said chamber and anindependent quantity control valve positioned to control flow throughsaid passage, said -valve being normally open to permit flow but'adapted to be closed to prevent ow at desired times in the pump cycle,a plunger in said pump and means for driving it, a drive for saidcontrol valve to move it into a closed position and to release it formovement to its normally open position, resilient means in said controlvalve drive, Said resilient means being preloaded to transmit vthedriving force of said drive and support the valve in closed positionagainst predetermined pressure existing in said third passage when saidvalve is in closed position, said drive including means forindependently varying the times at which said control valve is movedinto closed position and the times of releasing it for movement to itsnormally open position.

PHILIP LANE SCOTT.

